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*GL3.2 for AIX: Graphics Library (GL) Technical Reference*

## curveit Subroutine

### Purpose

Draws a curve segment by iterating the forward difference matrix.

### Libraries

Graphics Library

C (**libgl.a**)

FORTRAN (**libfgl.a**)

### C Syntax

**void curveit(Int16 ***count***)**

### FORTRAN Syntax

**SUBROUTINE CURVEI(***count***)**
**INTEGER*4 ***count*

**Note: **For FORTRAN users, this subroutine accepts long integer parameters (INTEGER*4) when invoked from a FORTRAN program, although it accepts short integers when invoked from a C program. The C and FORTRAN syntax shown here reflect this difference.

### Description

The **curveit** subroutine repeats the
forward difference algorithm with the current matrix (the one on top of the matrix stack) for the number of times assigned by the *count* parameter. Each iteration draws one of the line segments that approximate the curve. The **curveit** subroutine accesses low-level hardware capabilities for curve drawing.

### Parameter

*count* |
Specifies the number of times to repeat the current matrix. |

### Example

The example C language program **curve3.c** uses the **curveit** subroutine to draw a Bezier curve segment after building the correct transformation matrix.

### Implementation Specifics

This subroutine is part of GL in the AIXwindows Environment/6000 Version 1, Release 2 with AIXwindows/3D Feature.

### Files

**/usr/include/gl/gl.h** |
Contains C language constant and variable type definitions for GL. |

**/usr/include/gl/fgl.h** |
Contains FORTRAN constant and variable type definitions for GL. |

### Related Information

Drawing a cubic spline curve with the **crv** subroutine.

AIX Graphics Library Overview, Drawing NURBS Curves and Surfaces, and Drawing Wire Frame Curves and Surface Patches.

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